Can I find out my gears without dismantling

[Zach P.]

My car has a different rearend than was installed by the factory and was wondering if there is a way to find out what the gears are without tearing apart the rearend. also the speedo is off, at 55mph it is at about 70 according to my gps can this be tuned to be corrected?

[dozerdan]

yes it can.

[dozerdan]

does the car have any kind of tune on it now?

[Zach P.]

the dealership looked with there computer to make sure that it was firing on all cylinders and said that the tune was stock but I'm not sure, wsurely it would need a tune to run decent with heads cam and headers, but I don't know.

[dozerdan]

the dealer can't see shit as far as a tune from what i understand. bring it up here sometime and we'll scan it and see what its got

[Daniel P.]

what is the name of your shop, where exactly is loyal?

I'm zach's cousin and turned him onto the site, his laptop is havin problems on our wireless so i answer for him.

[Jays00ss]

lift your rear end up and have your tranny in Neutral. Spin your wheels. for every 1 rotation of your back wheel, divide how many revolution your drive shaft turns.

For instance, If your drive shaft makes 4 revolutions when your wheel goes around once, you more than likely have 4.10 gears. Gives you a rough estimate.

[Zach P.]

Thanks for the help.

[01blackbird]

Keep in mind what jays00ss mentioned is a very good estimate but it only works out that way if you have a posi. With you having a different rear end in your ride, you never know, it could be a non-posi. Not to likely but I'd thought I'd let you know.

[Benner]

You should be able to find out the gear ratio by the RPO codes on the car. A tune should be able to recalibrate the Speedo and if you have heads/cam you definately need a tune to get close to everything out of the car.

[01Z28M6]

Keep in mind what jays00ss mentioned is a very good estimate but it only works out that way if you have a posi. With you having a different rear end in your ride, you never know, it could be a non-posi. Not to likely but I'd thought I'd let you know.Even with a "posi" the wheels can rotate in opposite directions. A working auburn will spin both wheels together but if it is the Zexel, the wheels will turn like an open differential - rotating opposite like you said.

The way to do it with ANY differential is to put the car up in neutral - mark the driveshaft and either tire that turns with the shaft. Then rotate the driveshaft by hand or a small lever through a U joint. If it's a 2.73 the shaft marker will turn over 2 and 3/4 times per wheel rotation, 3.23 - 3 and 1/4 times; 3.42 almost 3 and 1/2 times etc....